The presence of radiation in West Coast waters from the 2011 Fukushima nuclear reactor release is expected to peak in 2015-16, yet remain far below a level that poses health risks to humans or animals.
A paper published by Fisheries and Oceans Canada scientist Dr. John Smith in the Proceedings of the National Academy of Sciences in December, 2014, details the arrival and concentration of radioactive isotopes Cs-134 and Cs-137 from Fukushima Daichi-1 in the North Pacific Ocean.
The reactor was damaged in the magnitude 9.0 earthquake and resulting tsunami that struck off the coast of Japan in March, 2011. That resulted in the release of a radioactive plume from Fukushima Daichi-1 into the atmosphere and water of the North Pacific Ocean. In the first three years following the incident, levels of Cesium 137 have risen to two becquerels per cubic metre of water from normal background readings of one becquerel per cubic metre, Smith wrote.
Those levels are projected to peak at approximately five becquerels in the coming year before gradually returning to background levels. To put that figure in perspective, DFO notes, Canada’s standard for Cesium-137 in drinking water is 10,000 becquerels per cubic metre.
Following the 2011 earthquake and tsunami, DFO established an ocean monitoring program to validate ocean circulation models and trace the arrival of Fukushima radioactivity. That system has grown to include 80 monitoring stations in the Strait of Georgia and Juan de Fuca.
The monitoring system tests not only for the presence of radiation, but for a variety of physical, chemical and biological properties of the water at varying depths.
“One of the reasons that we undertake this survey, is that we’re interested in understanding the oceanography of the region, and by monitoring the ocean we can identify changes that are occurring, which may be indicators of the ecosystem being at risk,” said Peter Chandler, a physical oceanographer.